The present invention relates to a looper thread control device for a chain stitch sewing machine.
Looper thread control devices for a chain stitch sewing machine are known. In such devices, a looper thread is fed between thread eyes across rotatable discs which, as a result of their contour, feed thread to and from the looper in order to cause perfect stitch formation.
However, these thread control devices can be disadvantageous if the looper thread breaks. If the thread breaks in known looper thread control devices, the rotating discs may pick up the loose thread and wind it up. By the time the operator has noticed the break, a large quantity of thread may already be wound up, thus requiring a long period of time to remove the wound thread.
In order to prevent the broken thread from being wound up, it has been proposed to clamp the looper thread in front of the discs such that the thread can be broken off should it start to be wound up. However, this device is relatively expensive, since it requires parts which move in synchronism with the stitch formation.